On Heat Set Inserts

I’ve been tinkering with my 3D printer and have found myself quite enamored with the notion of adding heat set screw inserts into 3D printed PLA parts. I’ve spent a fair amount of time mastering the technique and I thought I’d share some insights here, in case it proves helpful for anyone else.

The What and Why of Heat Set Screw Inserts

Heat set screw inserts are nifty little brass threads that you can embed into your 3D printed parts. Their purpose? To create durable, reusable threads for machine screws. This is particularly handy when you’re building parts that need to be assembled and disassembled multiple times, as PLA threads can wear out quickly. Heat set screw inserts provide a stronger, metal thread that can withstand repeated use.

M2 inserts
Product image: M2 heat set inserts

Let’s talk about the tools

Firstly, you’re going to need a soldering iron. This is used to heat up the insert, which is then pressed into the plastic. The plastic melts and then solidifies around the insert, creating a secure hold.

You might be wondering, “Why not just use a heat gun?” The answer lies in precision. With a soldering iron, you can have pinpoint accuracy, ensuring the insert goes in straight and to the right depth. A heat gun, on the other hand, could melt parts of your print that you didn’t intend to. This is how you wind up with a puddle!

Alongside your soldering iron, you’ll also need a tip specifically designed for heat set inserts. This tip has a small protrusion at the end that fits into the insert and holds it in place. If you don’t have access to a specific heat-set insert tip, don’t fret! A standard tip can work too, although it won’t work well.

Down to business

Let’s get down to the nitty-gritty, shall we? You’ve got your 3D printed part, your heat set insert, and your soldering iron all ready to go.

First, warm up your soldering iron. You don’t want it too hot – around 200°C should do it. Too hot and you might burn the plastic, too cold and the insert won’t go in smoothly.

Once your iron is up to temperature, you’re ready to start. Place the insert onto the end of the soldering iron, making sure it’s straight. Then, position the insert over the hole in your 3D printed part. Apply gentle pressure and the insert should start to sink into the plastic.

The trick here is to go slow. You want the insert to melt its way into the part, not to force it. If you push too hard, you might end up with a skewed insert or, worse, damage your part. It’s also worth noting that your hole should be slightly smaller than the insert to ensure a tight fit.

As the insert sinks into the plastic, keep a keen eye on it. Once the top of the insert is flush with the surface of the part, remove the soldering iron and allow the part to cool. Voila! You’ve installed a heat set screw insert.

Here are a few extra tidbits I’ve picked up along the way.

  1. If you’re inserting multiple heat set screws, work from the inside out. This prevents the part from warping due to heat.
  2. If your insert gets skewed, quickly remove the soldering iron, let the part cool, and then reheat and readjust the insert.
  3. Finally, practice makes perfect. Try a few test inserts on a scrap piece of PLA before moving on to your actual part.

In Closing

With a bit of practice, adding heat set screw inserts to your 3D printed PLA parts can be a straightforward process. Not only do they add strength and longevity to your prints, but they also give your projects a professional, polished look.

I’ve been off doing videos, but sometime in the future, I may put one together demonstrating the process for those of you who are more visually inclined. In the meantime, happy printing and inserting!

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